In the five contested GOP nominating races from 1980 forward, the Hawkeye State has gone for the eventual nominee only twice: It gave first-place finishes to Midwestern favorite Bob Dole in 1996 and to consensus front-runner George W. Bush in 2000.

In other years, the Republican caucuses have proved an uncertain trumpet. In 1980, Iowa Republicans favored George H.W. Bush narrowly over eventual nominee Ronald Reagan; in 1988, Iowa chose Dole - and consigned Bush, Reagan’s VP and eventual successor, to third, well behind televangelist Pat Robertson. In 2008, eventual nominee John McCain, who had limited his efforts here to focus on New Hampshire, finished fourth, behind winner Mike Huckabee, Mitt Romney, and Fred Thompson.

Here’s one thing that can be said with near certainty about next week’s caucuses: They will play a winnowing role among the three lesser candidates vying to become the favorite of committed religious and social-issue conservatives.

Indeed, Iowa has already claimed one early victim in that intra-caucus contest: Tim Pawlenty of next-door Minnesota dropped out in August after fellow Minnesotan Michele Bachmann (and Ron Paul) beat him in the Ames Straw Poll. Several others will likely be rendered the walking wounded on Jan. 3. One could well be Bachmann herself, who has emerged as a factually challenged fringe candidate. Or the floundering Rick Perry, who after a recent appeal to religious conservatives, is positioning himself as an anti-Washington populist with new TV ads that inveigh against Congress: “Cut their pay in half! Cut their time in Washington in half! Cut their staff in half!’’ (Why stop there? Cut them in half!)

After long months of toiling in near-obscurity, Rick Santorum seems to be closing well here, which could render him the religious/social conservative who has his post-Iowa ticket punched. But to where? Like Bachmann and Perry, Santorum has shown little appeal in New Hampshire. Further, that positioning usually puts a candidate on a dead-end road.

So how could Iowa play a bigger role this year? Simple: By boosting a candidate who has a realistic chance at winning the nomination. Mitt Romney tops that list. After months of low-balling his Iowa expectations, Romney is now making a concerted final-week push here. If he could pull off a victory, it would solidify his standing in New Hampshire and put him in the catbird seat going forward.

Conversely, if Newt Gingrich were to pull out a win, it would demonstrate that he’s for real in the race for the nomination, and not just the latest Anybody-But-Mitt prospect to bob to the surface in the current of conservative discontent. A Gingrich victory here would frame New Hampshire as a real battle between the two.

Say this for Newt: He knows that Iowa is capital of the Polite Belt. And so, after a long career as a snarling pit bull, he’s gone strategically positive. He’s now airing an ad that sorrowfully chides his rivals for being “more focused on attacks’’ than on “moving the country forward.’’ In other words, for acting precisely the way he long has.

Finally, there’s Ron Paul, who sits at or near the top of a divided field, even as renewed focus on racially tinged newsletters once sent under his name have raised serious questions about both his views and his candor.

Paul can rightly claim to be winning converts to his libertarian cause. But for all the much-praised consistency of his positions, those same views frequently wander into the realm of the outdated, the impractical, or the downright absurd.

It’s impossible to imagine the 76-year-old libertarian becoming president. It’s almost as hard to imagine him becoming the GOP nominee. Should he win here, it will merely defer the GOP’s real decision - and signal that, once again, Iowa is marching to a different drummer.